Order to advance rapidly with intelligence over border (5,5)
I believe the answer is:
quick march
'order to advance rapidly' is the definition.
(military order)
'with intelligence over border' is the wordplay.
'with intelligence' becomes 'quick' (quick can mean clever).
'over' is a charade indicator (letters next to each other).
'border' becomes 'march' (term for a border eg the Welsh Marches).
'quick'+'march'='QUICK MARCH'
(Other definitions for quick march that I've seen before include "may be part of a tattoo?" , "Military command (to step on it!)" , "Order for soldiers to move" , "Military movement order (to foot soldiers?)" .)